# COST06-BP04 - Consider using shared resources

Best practice: COST06-BP04
Pillar: Cost Optimization
Source: https://wellarchitected.cloudvisor.eu/docs/cost-optimization/cost06-bp04.html

## Implementation guidance

Where workloads or components have compatible requirements, share resources
instead of provisioning dedicated capacity for each one. Sharing increases
aggregate utilization, smooths out per-workload peaks and troughs, and lowers
the total resource type, size, and number needed to meet your cost targets.

### Identify sharing opportunities

**Group compatible workloads**: Look for workloads with complementary demand
profiles (for example, batch jobs that run overnight alongside interactive
workloads that peak during the day) that can safely share the same underlying
capacity.

**Use multi-tenant and managed services**: Prefer services that pool capacity
across tenants — for example, container platforms (Amazon ECS/EKS) bin-packing
multiple tasks onto shared compute, serverless services that share the
underlying fleet, or shared databases and clusters — rather than standing up
isolated infrastructure per workload.

### Manage shared resources safely

**Right-size the shared pool**: Size shared capacity to the aggregate demand of
the tenants, taking advantage of statistical multiplexing rather than summing
each workload's individual peak.

**Isolate and attribute**: Apply appropriate isolation (namespaces, quotas,
limits) so one tenant cannot starve another, and use split cost allocation data
and tagging so shared cost is attributed fairly back to each consumer.

**Validate against requirements**: Confirm that sharing does not violate
performance, security, or compliance requirements before consolidating
workloads onto shared resources.

## AWS Services to Consider

<div class="aws-service">
  <div class="aws-service-content">
    <h4>Amazon ECS / Amazon EKS</h4>
    <p>Bin-pack multiple tasks or pods onto shared compute to raise utilization and reduce the number of instances required.</p>
  </div>
</div>

<div class="aws-service">
  <div class="aws-service-content">
    <h4>AWS Lambda &amp; serverless services</h4>
    <p>Share an underlying managed fleet across many workloads, paying only for what each invocation consumes.</p>
  </div>
</div>

<div class="aws-service">
  <div class="aws-service-content">
    <h4>Split cost allocation data</h4>
    <p>Attribute the cost of shared container and other resources back to individual workloads for fair chargeback.</p>
  </div>
</div>

## Related Resources

<div class="related-resources">
  <ul>
    <li><a href="https://docs.aws.amazon.com/wellarchitected/latest/framework/cost_type_size_number_resources_shared.html">AWS Well-Architected — COST06-BP04 Consider using shared resources</a></li>
    <li><a href="https://docs.aws.amazon.com/wellarchitected/latest/framework/cost-06.html">COST06: How do you meet cost targets when you select resource type, size, and number?</a></li>
  </ul>
</div>